Small Engines (Lawn Mowers, etc.): leaking oil, engine model type, briggs and stratton

Question
i have a statesman mtd riding mower and recently it starting leaking oil from bottom of motor. took motor off and found bolts that were loose. tighten them up and still leaking. what do i need to do? model# 135h670f016, serial# 1l084h30120

Answer
What brand of engine is on the mower, Briggs, Tecumseh, Kohler?  What is the engine model, type and code number?  Looking at the parts list it looks likes you have a Briggs and Stratton engine.

The problem you have is fairly common.  Briggs resolved this issue, the bolts coming loose, with later models by adding lock washers and applying Loctite thread locker to the bolt threads.

To fix your problem you will need to replace the engine to sump/oil pan gaskets.  The gaskets usually crack/break when the bolts come loose.  It's not a hard job, but takes some time.  Since you need to remove the oil sump, I'd replace the lower main oil seal as well.  When reassembling, clean the bolt threads and bolt holes with parts/brake cleaner and apply Loctite 242 (or similar) to the bolt threads when reassembling so the bolts will not back out again.

Let me know if this helps.

Eric